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5 Turtlebots

Each group will have a Turtlebot. Each robot is numbered. The number specifies the IP address and ID of the discover server running on the robot.

The IP address of the robot's server will be: 192.168.0.IP where IP = 20 + robot_number.

The ID matches one to one with the ID of the server.

Note

Make sure to open new terminal windows with clean environments to avoid potential conflicting environment issues.

Terminal 1: Teleop Turtlebot

Set the robot server in the discovery server variable:

export ROS_DISCOVERY_SERVER=”;192.168.0.<IP>:11811”

Note

You need to add N number of ; to set the correct the ID.

Examples:

export ROS_DISCOVERY_SERVER="192.168.0.20"            # Robot 00
export ROS_DISCOVERY_SERVER=";192.168.0.21"           # Robot 01
export ROS_DISCOVERY_SERVER=";;192.168.0.22"          # Robot 02
export ROS_DISCOVERY_SERVER=";;;192.168.0.23"         # Robot 03
export ROS_DISCOVERY_SERVER=";;;;192.168.0.24"        # Robot 04
export ROS_DISCOVERY_SERVER=";;;;;192.168.0.25"       # Robot 05
export ROS_DISCOVERY_SERVER=";;;;;;192.168.0.26"      # Robot 06
export ROS_DISCOVERY_SERVER=";;;;;;;192.168.0.27"     # Robot 07
export ROS_DISCOVERY_SERVER=";;;;;;;;192.168.0.28"    # Robot 08
export ROS_DISCOVERY_SERVER=";;;;;;;;;192.168.0.29"   # Robot 09
export ROS_DISCOVERY_SERVER=";;;;;;;;;;192.168.0.30"  # Robot 10
export ROS_DISCOVERY_SERVER=";;;;;;;;;;;192.168.0.31" # Robot 11

Then, set the terminal as super client:

export ROS_SUPER_CLIENT=1

Restart the daemon and ensure you are able to see all of the robot's nodes and topics:

ros2 daemon stop; ros2 daemon start;
ros2 node list
ros2 topic list

Now, you can drive the Turtlebot:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r __ns:=/<tb_ns>

Bandwidth (Optional)

Terminal 1: Camera Test

Install the FFMPEG image transport plugin:

sudo apt install ros-humble-ffmpeg-image-transport

Try to retrieve the camera topic:

ros2 topic hz /<tb_ns>/oakd/rgb/preview/image_raw

If you're lucky you might get some packets through. It is likely that no data will reach your device.

Instead, try the FFMPEG topic which has encoded image data.

ros2 topic hz /<tb_ns>/oakd/rgb/preview/image_raw/ffmpeg

You won't be able to view the image data in RViz while it is encoded. Instead, decode it using the republisher node:

ros2 run image_transport republish ffmpeg in/ffmpeg:=/<tb_ns>/oakd/rgb/preview/image_raw/ffmpeg raw out:=/<unique_namespace>/oakd/decoded/image

Now, you should be able to get the image data as a standard image topic:

ros2 topic hz /<unique_namespace>/oakd/decoded/image
ros2 topic bw /<unique_namespace>/oakd/decoded/image

Then, open RViz and view the image:

rviz2